Electrophotographic reproduction of a three-dimensional object

ABSTRACT

A method and apparatus for making a two-dimensional copy from either a two-dimensional or three-dimensional object is provided. In making a two-dimensional copy from a three-dimensional object, the object is submerged in the liquid contained in a container having a transparent bottom portion to which the object is brought into contact by placing a cover member thereon. The object is then exposed through the transparent bottom portion thereby the projected image of the object viewed through the transparent bottom portion is reproduced on a sheet of copy paper.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of prior U.S. application Ser. No.342,471, filed Jan. 25, 1982, now U.S. Pat. No. 4,454,210.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to electrophotographic reproductionand more in particular to an electrophotographic reproduction method andapparatus which is capable of making two-dimensional copies of athree-dimensional object.

2. Description of the Prior Art

Prior art electrophotographic copying machines are usually built to maketwo-dimensional copies from a two-dimensional original such as a book orsheet of paper. In such prior art copying machines, in-focus conditionsare satisfied when a two-dimensional original is properly placed on thetop surface of the contact glass plate. However, since the opticalsystem of the prior art copying machines usually has a limited orshallow field of depth, they are not suited for making two-dimensionalcopies of a three-dimensional object, i.e., making a copy of theprojected image viewed in one direction of a three-dimensional object ona sheet of copy paper.

It has often been required to make two-dimensional copies of athree-dimensional object. For example, in a surgical operation, autopsyand the like, internal organs removed from the patient or dead body arepreserved as specimens in spirits at least partly. However, more oftenthan not, photographic pictures of the removed organs are taken with theuse of a special photographic device for internal organs so that thepictures may be filed together with related medical certificates orreports.

It is true that such a special photographic device is equipped withmeans for adjusting the field of depth of its lens in multiple steps bymaneuvering its optical system. However, such means for adjusting thefield of depth is rather complicated in structure and thus it tends tobe expensive as well as unreliable. Moreover, such a prior art devicerequires a relatively long period of time for processing such asdeveloping and printing, and its result cannot be checked on the spot.If a required portion has been found to be insufficiently photographed,rephotographing can be made only with difficulty and insufficiency. Incertain circumstances, rephotographing is impossible or meaninglessbecause of the decay or disposal of the removed organ in question.

It should further be noted that the image on a photographic picture isusually reduced in size and it may be too small to examine certain partsof the photographed object. Besides, difficulties are often encounteredin recognizing the actual size of the photographed object. Such apicture is disadvantageous because notes cannot be written thereon.Another disadvantage is that its usage is rather limited and thereforethere are many occasions where such a special photographic device is notapplicable, though it is an expensive device.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided an electrophotographic method for making a two-dimensional copyof a three-dimensional object, said method comprising the steps of:immersing said object into a transparent liquid contained in a containerhaving a transparent bottom plate; placing a cover member having a whitebottom surface on said object thereby bringing said object partly incontact with said bottom plate, any part of the bottom surface of saidcover member being under the water surface of said liquid; and exposingsaid object through said transparent bottom plate to a photosensitivemember in order to apply a series of electrophotographic process stepsto said photosensitive member to obtain a two-dimensional copy image ofsaid three-dimensional object.

In accordance with another aspect of the present invention, there isprovided a container for containing therein a three-dimensional objectin order to make a two-dimensional copy thereof, said containercomprising a bottom having a transparent portion to which said object isto be brought into contact, a sidewall extending upward from theperiphery of said bottom and having an inner reflecting surface, firstfastening means fixedly mounted on said bottom or sidewall, a flexiblecover member having a reflecting surface and second fastening meansengageable with said first fastening means whereby said object is set inposition in contact with said transparent portion by said cover memberwhen said first and second fastening means are brought into engagement.

In accordance with a further aspect of the present invention, there isprovided an electrophotographic copying machine having a normal copymode in which two-dimensional copies are made from a two-dimensionaloriginal as usual and a three-dimensional copy mode in whichtwo-dimensional copies are made from a three-dimensional object, saidcopying machine comprising a photosensitive member; image forming meansincluding charging means for charging the surface of said photosensitivemember, exposure means for exposing the thus charged photosensitivemember to said two-dimensional original or the projected image of saidthree-dimensional object to form an electrostatic latent image, anddeveloping means for developing said latent image thereby convertinginto a visual image; and switching means for switching between saidnormal copy mode and three-dimensional copy mode, said switching meanschanging the conditions of at least one of said image forming means whenthe modes are switched.

There is also provided an electrophotographic copying machine capable ofmaking a two-dimensional copy either from a two-dimensional orthree-dimensional object comprising holder means defining a holdingsurface on which said object may be placed; a photosensitive member; anoptical system for leading the light reflected from said object to thesurface of said photosensitive member, said optical system includingadjusting means for adjusting to hold the conjugate image formingrelation between said holding surface and the surface of saidphotosensitive member and between a point located above said holdingsurface and the surface of said photosensitive member; andelectrophotographic processing means including charging means anddeveloping means to be applied to said photosensitive member in formingan image thereon.

It is therefore an object of the present invention to provide a processand apparatus capable of making two-dimensional copies from either atwo-dimensional or three-dimensional object.

Another object of the present invention is to provide a process andapparatus capable of obtaining the projected image viewed in onedirection of an internal organ of an animal including a human being,dead or alive, on a sheet of paper.

A further object of the present invention is to provide a container forcontaining therein a three-dimensional object such as an internal organfrom which a two-dimensional copy is to be made.

A still further object of the present invention is to provide anelectrophotographic copying machine which has a normal mode in whichtwo-dimensional copies are made from a two-dimensional original and athree-dimensional copy mode in which two-dimensional copies are madefrom a three-dimensional object.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration showing one embodiment of the presentinvention;

FIG. 2 is a perspective view showing one form of the container forcontaining therein a three-dimensional object such as an internal organfrom which a two-dimensional copy is to be made;

FIG. 3 is a perspective view showing the container of FIG. 2 in use witha part of the cover member appearing above the height of the sidewall;

FIG. 4 is a schematic illustration showing a sheet of copy paper whichis obtained by carrying out a reproduction process with the conditionshown in FIG. 3;

FIG. 5(A) is a top plan view showing another form of the container;

FIG. 5(B) is a cross-sectional view of the container shown in FIG. 5(A);

FIG. 6 is a fragmentary view showing a part of the container on anenlarged scale shown in FIG. 5(A);

FIG. 7 is a perspective view showing an alternative example of the covermember forming a part of the container shown in FIG. 5(A);

FIG. 8 is a schematic illustration showing another embodiment of thepresent invention which particularly illustrates the switching mechanismbetween the normal copy mode and the three-dimensional copy mode;

FIG. 9 is a schematic illustration showing on an enlarged scale a partof the structure shown in FIG. 8;

FIG. 10 is a graph showing the relationship between density and slitwidth for the normal and three-dimensional copy modes;

FIG. 11 is a schematic illustration showing the structure in whichprovision is made of the developing electrode movable between twopositions depending upon the mode of operation, normal orthree-dimensional, in accordance with the present invention;

FIG. 12 is a schematic illustration showing the structure in which thelevels of voltages applied to the exposure lamp and the developingelectrode are changed depending upon the mode of operation, normal orthree-dimensional, in accordance with the present invention;

FIG. 13 is a schematic illustration showing one embodiment of thepresent invention having an adjustable optical system;

FIG. 14 is a schematic illustration showing a driving system for movingthe mirrors 41 and 42 shown in FIG. 13;

FIG. 15 is a schematic illustration showing another embodiment of thepresent invention having an adjustable optical system;

FIG. 16 is a schematic illustration showing a further embodiment of thepresent invention having an adjustable optical system;

FIG. 17 is a schematic illustration showing a still further embodimentof the present invention having an adjustable optical system; and

FIG. 18 is a schematic illustration showing a still further embodimentof the present invention having an adjustable optical system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is schematically shown anelectrophotographic copying machine which includes a container 1 havinga transparent bottom plate 1a. A quantity of transparent liquid 2 suchas water and formalin is contained in the container 1. Pivotallyprovided is a cover member 3 which is preferably comprised of asynthetic resin and has a bottom surface white in color.

A three-dimensional object 4, such as an internal organ, from which acopy is to be made is placed as submerged in the liquid 2 inside thecontainer 1. The object 4 is in light pressure contact with the bottomplate 1a because of the weight of the cover member 3. It is to be notedthat the cover member 3 or at least any part of its bottom surface mustbe submerged in the liquid 2. The cover member 3 is not necessarilyflexible, but it is preferable to be flexible particularly in the casewhen the object 4 is irregular in shape.

Disposed below the container 1 is a photosensitive drum 5 which isdriven to rotate in the direction indicated by the arrow a at a constantspeed V. Disposed between the container 1 and the drum 5 is an exposuresystem 6 which includes an illumination lamp 6a, a first travellingmirror 6b, a second travelling mirror 6c, an in-mirror lens 6d and afourth mirror 6e. The light reflected from the object 4 impinges uponthe surface of the drum 5 at the exposure position as reflected by themirror 6b, mirror 6c, lens 6d and mirror 6e in the order mentioned. Itis to be noted that the first travelling mirror 6b together with thelamp 6a is movable in the direction indicated by the arrow b or itsreverse direction. Likewise, the second travelling mirror 6c is movablein the direction indicated by the arrow c or its reverse direction. Whenthe first travelling mirror 6b together with the lamp 6a moves in thedirection indicated by the arrow b with speed V, the second travellingmirror 6c moves in the direction c, which is the same as the directionb, with speed V/2 synchronously. In this manner, slit scanning of theobject 4 can be carried out.

Disposed along the peripheral surface of the photosensitive drum 5 are acharging device 7, a developing device 8, a transferring device 9, aseparating device 10, a cleaning device 11 and a discharging device 12.Thus, as the drum 5 rotates, the peripheral surface of the drum 5 isuniformly charged by the charger 7 and then the thus charged surface isexposed to a light image from the object 4 to form an electrostaticlatent image. Then, the latent image is developed by the developingdevice 8 to form a toner image which is then transferred to a transfermedium with the aid of the transferring device 9. The transfer medium isthen separated from the drum 5 to be transported to a desired place;whereas, the drum 5 is subjected to the cleaning operation by thecleaning device 11 to remove any residual toner. Thereafter, the drum 5is discharged by the discharging device 12 thereby preparing for a nextcycle of copying operation.

As shown in FIG. 2, a scale 12 is provided on the bottom plate 1a alongits one side. A slot 13 is formed at one corner of the container 1 andthus an insert with words or numbers identifying the object 4 may beslipped into the slot 13. As shown, the container 1 is mounted on thehousing 14 of the copying machine and a liquid receiver 15 generally inthe shape of a letter "L" is also mounted on the housing 14 with twosidewalls in contact with the corresponding sidewalls of thecontainer 1. The liquid receiver 15 is provided to receive drippingliquid droplets when the object 4 is moved in or out of the container 1thereby preventing the liquid from getting inside of the copyingmachine. The liquid receiver 15 has a bottom plate 15a which is providedwith a pair of recesses 15b, 15b. On the other hand, the housing 14 isprovided with a pair of projections (not shown) which may be fitted intothe corresponding recesses thereby placing the liquid receiver 15 inposition. It should be noted that the container 1 may be placed on thecontact glass, which forms a holder for holding thereon an original, ofthe copying machine.

With the structure described above, a clear projected image of thethree-dimensional object 4 can be obtained on a sheet of copy paper. Therefractive index of the liquid 2 is larger than that of the air, thefield of depth of the lens system becomes effectively deeper and therate of reflection of the illuminating light increases. It is believedthat this allows to obtain a clear two-dimensional copy of athree-dimensional object.

As shown in FIG. 3, if the internal organ 4 is rather large, there willbe formed a gap d between the cover member 3 and the sidewall 1b,thereby allowing leakage of the illuminating light. If a copy isproduced under such condition, "black" areas will appear on a copy sheetP as shown in FIG. 4. Moreover, if the internal organ 4 has a relativelylarge buoyancy, the operator must lightly press the cover member 3 downto keep the internal organ 4 in contact with the bottom plate 1a withhis or her hand.

In view of the above, FIGS. 5 through 7 illustrate an improved container20 for placing therein the internal organ 4 from which a two-dimensionalprojected image is to be formed on a sheet of copy paper. As shown, thecontainer 20 includes a transparent bottom plate 21 which may be placedin contact with the contact glass 14a mounted on the copy machinehousing 14. The container 20 also includes a raised bottom portion 22formed around the bottom plate 21 as raised approximately by 20 mm, asidewall 23 extending upward from the outer periphery of the raisedbottom portion 22 and a pair of holders 24 extending oppositely in theoutward direction from the sidewall 23. The container 20 is integrallyformed by a material which is "white" in color in order to have anexcellent reflecting surface except at the bottom plate 21.

A cover member 28 is preferably made of a flexible material such asrubber and synthetic resin, and it is placed on the internal organ 4 tobring it into a light pressure contact with the bottom plate 21. Forexample, the cover member 28 may be made from a sponge material with itsone surface spread with white rubber and then vulcanized. The covermember 28 may also be made from other materials, but it is preferably of0.5 to 4.0 mm thick. The cover member 28 has such a size that it may befitted into the container 20 with its side portions riding on thecorresponding raised bottom portions 22. The cover member 28 is providedwith four fastening devices 29 one for each side. Similarly, fourfastening devices 25 are attached to the raised bottom portions 22.After placing the cover member 28, the fastening devices 29 may bepressed into engagement with the respective fastening devices 25 byfingers so that the cover member 28 and thus the internal organ 4 may beheld in position. The engagement between the fastening devices 25 and 29is such that they may be easily disengaged by pulling the cover member28 outwardly by fingers. Also provided is a detachable memo plate 26 onwhich may be written desired items such as date and I.D. number.Besides, a scale 27 is provided on the bottom plate 21.

In use, a quantity of transparent liquid W such as water is poured intothe tray-like container 20 placed on the contact glass 14a of thecopying machine, and then the internal organ 4 from which a projectedimage to be obtained is submerged in the liquid W. In turn, one of thefastening devices 29 attached to the cover member 28 is pressed intoengagement with the corresponding fastening device 25 attached to theraised bottom portion 22. Then, the cover member 28 is spread to coverthe internal organ 4 and that fastening device 29 opposite to thefastening device 29 already fastened is pressed into engagement with thecorresponding fastening device 25 on the raised bottom portion 22 assomewhat pulling the cover member 28 toward the fastening devices whichare going to be fastened together, thereby imparting a light pressureonto the internal organ 4 against the bottom plate 21. Thereafter, theremaining fastening devices are pressed into engagement. With such astructure, the internal organ 4 may be held in position properly andthere is no likelihood of occurring leakage of the illuminating lightpassing through the transparent bottom plate 21 because of the overlapbetween the cover member 28 and the raised bottom portion 22. Uponcompletion of reproduction, the cover member 28 may be easily removedjust by pulling in the upward direction for washing or cleaning.

FIG. 7 shows a modification of the cover member 28, in which only a pairof fastening devices 29, 29 is provided oppositely along the longersides because these are the sides which are more likely to leak theilluminating light. One end or shorter side of the cover member 28 shownin FIG. 7 is provided with a pair of pins 28a which may be temporarilyengaged with the correspondingly formed portions of the container 20.However, such pins 28a may be omitted because the shorter sides tend toproperly come into contact with the raised bottom portion 22 by theirown weight. It should also be noted that any conventional fasteningdevices may be appropriately selected for use for the purpose of thepresent invention.

FIG. 8 shows the electrophotographic copying machine having a switchingmechanism between the normal copy mode, in which a two-dimensional copyis produced from a two-dimensional original, and the three-dimensionalcopy mode, in which a two-dimensional copy is produced from athree-dimensional original. It is to be noted that like numeralsindicate like elements as practiced throughout this specification. Asnoticed, the structure of FIG. 8 is similar to the structure of FIG. 1.However, as shown in FIG. 8, there is newly provided an aperture plate30 which is pivoted at the exposure position and, as is well known,connected to a density adjusting knob 31 disposed at an appropriateposition of the copying machine through a wire 32. As will be describedbelow, however, the aperture plate 30 is also controlled by the modeswitching mechanism of the present invention.

FIG. 9 shows the detailed structure of one embodiment of the presentmode switching mechanism. As shown, a switching lever 33 in the shape ofa bell crank is pivotally supported in the neighborhood of the wire 32extended between the aperture plate 30 and the density adjusting knob31. Due to the recovery force of a coil spring 33a, the switching lever33 normally takes the inoperative position indicated by the solid linewhere the lever 33 stays away from the wire 32. However, when thecontainer 1 is placed in position, an actuating lever 34 is presseddownward so that the switching lever 33 is pivoted counterclockwiseagainst the force of the spring 33a through engagement with the bottomend of the actuating lever 34 to take the operative position, asindicated by the two-dotted line, where a pulley 33b rotatably supportedat the forward end of the switching lever 33 pushes the wire 32 to theright. As a result, the aperture plate 30 is pivoted clockwise to takethe wide-open position indicated by the two-dotted line so that a largeramount of light may impinge upon the photosensitive drum 5.

Returning to FIG. 8, disposed below the photosensitive drum 5 is aliquid developing device 8' which includes a developing plate 8a'constituting a counter electrode. As best shown in FIG. 11, thedeveloping electrode 8a' is pivotally supported and its one end isconnected to an adjusting knob 35 disposed at an appropriate position ofthe copying machine through a wire 36. Thus, the gap between the drum 5and the developing electrode 8a' may be appropriately adjusted.

In operation, a quantity of transparent liquid W such as water andformalin is poured into the container 1 and the internal organ 4 removedfrom the body of the patient is put into the liquid W inside thecontainer 1. Then, the container 1 is placed on the contact glass 14athereby the actuating lever 34 is pressed downward to pivot theswitching lever 33 counterclockwise so that the aperture plate 30 ispivoted clockwise to widen the slit width. In general, in the case of athree-dimensional object, from which an area image will be obtained on asheet of copy paper, the amount of reflected light will be smaller thanthat of a document which mainly includes line images. Therefore, theabove-described operation, in effect, is to compensate the amount oflight incident upon the drum 5 in the three-dimensional copy mode.

Under the circumstances, the density adjusting knob 31 may be munuallyoperated to further adjust the position or slit width of the apertureplate 30 in accordance with the color or other conditions of theinternal organ 4. The image density may be additionally controlled byadjusting the slit width as shown by the two-dotted curve in FIG. 10.Then, the cover member 3 is placed upon the internal organ 4 to bring itinto contact with the transparent bottom plate. Then a copy start buttonmay be depressed to start a copying cycle so that the lamp 6a travelshorizontally and its reflected light impinges upon the photosensitivedrum 5 through an optical system (not shown) thereby the projected imageof the internal organ 4 as viewed from the bottom is electrostaticallyformed on the photosensitive drum 5 as a latent image. Such a latentimage is then developed by the liquid developing device 8' so that adeveloped image of excellent tone representation without edge effectsmay be obtained due to the contributions from the electrophoreticfunction characteristic of the liquid developing technique and the biasvoltage applied to the developing electrode 8a'. Then, the thusdeveloped image is transferred to a sheet of copy paper.

If it is to be used as a part of the medical certificate, a copy imagemust faithfully and clearly indicate even wrinkles on the surface or anailing part of the internal organ. In such a case, the adjusting knob 35shown in FIG. 11 should be operated to move the developing electrode 8a'in the direction away from the drum 5 to decrease the strength of thefield formed by the bias voltage applied to the developing electrode andacting on the drum surface thereby allowing to reproduce the requireditems clearly on a sheet of copy paper. It is to be noted that it may beso structured to automatically position the developing electrode 8a' ata required position similarly with the density adjusting mechanismdescribed previously.

FIG. 12 shows another embodiment of the present invention. As shown, amagnet M is fixedly mounted on the container 1 and a magnet-operatedlead switch S is mounted on the copying machine at such position wherethe switch is closed when the container 1 is placed on the contact glass14a in position. When the switch S is closed, a larger voltage than thenormal copy mode is applied to the illumination lamp 6a through an inputvoltage control circuit 37 and at the same time a lower voltage than thenormal copy mode is applied to the developing electrode 8a' through abias voltage control circuit 38. However, depending upon thethree-dimensional object from which a projected image to be formed on asheet of copy paper, either one of the circuits 37 and 38 may beomitted, or either one or both of them may be constructed for manualoperation.

In general, the optical system of a copying machine is structured suchthat its focal point coincides with the top surface of the contact glassplate. Thus, by placing the surface of an original in contact with thetop surface of the contact glass plate, a clear copy image may beobtained. For this reason, anything such as a three-dimensional objecthaving portions which cannot be brought into contact with the topsurface of the contact glass cannot be properly shown on a sheet of copypaper produced. This is particularly true for such cases as bossedgears, cams, levers of irregular shape, printed circuit boads mountedwith components, ores, biological samples, fish and internal organscontained in a transparent container.

In the case of a copying machine which employs the lens of F=8, if themagnification ratio β=1 and the practically allowable resolving power δor diameter of minimum distraction circle is equal to 0.1, the field ofdepth d under the conditions may be calculated from the equation

    d=±F(1+β)δ

to be ±1.6 mm. Accordingly, if it is so adjusted that the sharpest imagemay be obtained at the top surface of the contact glass plate, it istrue that the field of depth in the order of 1.6 mm above the top platemay be obtained. However, the field of depth of this order is notsufficient for most of the items of interest, some of which are raisedabove. In addition, in the case of a copying machine which employs alighter lens such as F=4.5 to 4 as in the recent high-speed copiers, thefield of depth is shallower, which makes it even more difficult to theapplication for a three-dimensional object. If the field of depth isforcibly made larger by setting a smaller lens stop, it is then requiredto increase the level of illumination so as to make up for the loss oflight amount, which, in turn, could bring about another problem such asexcessive heating and large power consumption.

In view of the above, the present invention provides a copying machinecapable of showing those portions of a three-dimensional object thatcannot be brought into contact with the top surface of the contact glassplate on a sheet of copy paper produced with excellent clarity.

FIG. 13 shows one embodiment of the present invention and it includes afirst travelling mirror 41 which moves as a unit with an illuminationlamp along and inparallel with the contact glass plate 14a therebyslit-scanning the original surface located on the plate 14a or theoriginal surface located above at a distance l separated from the topsurface of the plate 14a. Also provided is a second travelling mirror 42which is a combined structure of a pair of mirrors arrangedperpendicular to each other. The reflected light comming from the firsttravelling mirror 41 is redirected by the second travelling mirror 42 toimpinge upon the photosensitive drum 5 after passing through a lens 43and reflection by a fixed mirror 44.

As well known in the art, the first and second travelling mirrors 41 and42 are driven to move with the velocities V and V/2, respectively. Inthe present embodiment, the mounting position of the second mirror 42may be shifted. For example, if a point of interest is located at adistance l above the contact glass plate 14a, the mounting position ofthe second mirror 42 is shifted to the left over a distance l/2 from thenormal position. By so doing, the optical length from a point g on thetop surface of the contact glass plate 14a to a point h on theperipheral surface of the drum 5 is maintained equal to the opticallength from a point g' separated from the top surface of the contactglass plate 14a over a distance l and the point h on the drum 5. Thus,the focal point has been moved to the point g'.

FIG. 14 shows a driving mechanism for the first and second mirrors 41and 42 and a position control mechanism for the second mirror 42. Thereis provided a driving pulley 51 which may be coupled to the drivingshaft of the photosensitive drum 5 through an electromagnetic clutch. Tothe pulley 51, one end of each of a pair of wires 58 (dotted line) and59 (solid line) is fixed. The wire 58 extends to the right from thepulley 51 in FIG. 14 and its the other end is fixed to a shift controlpulley 57 after passing around an idler pulley 52, a pulley 54 rotatablysupported on a carriage for carrying the second mirror 42 and an idlerpulley 55. On the other hand, the other wire 59 extends to the left fromthe pulley 51 in FIG. 14 and its the other end is fixed to the shiftcontrol pulley 57 after passing around an idler pulley 53, the pulley 54and an idler pulley 56. All of these pulleys are fixed in position andusually rotatably mounted on the machine housing except the pulley 54which is reciprocatingly movable with respect to the other. The pulleys55 and 56 are located approximately at two end positions of thereciprocating movement of the second mirror 42 or its carriage (notshown). The shift control pulley 57 is driven to rotate by means of astepping motor thereby controlling the amount of shift in position ofthe second mirror 42 with respect to the first mirror 41, which is fixedto a certain point of the wire 59.

In operation, in the normal copy mode, the shift control pulley 57 staysat its predetermined angular position and the second mirror 42 takes theposition indicated by the solid line in FIG. 13. Under the condition,when the driving pulley 51 rotates in the direciton indicated by thearrow A, the first mirror 41 moves to the left in the drawings along thescanning path with the peripheral velocity of the driving pulley 51through the wire 59; on the other hand, the second mirror 42 also movesto the left but with the velocity a half of the peripheral velocity ofthe driving pulley 51 so that the required operation of the opticalsystem is carried out. If it is desired to focus at a point locatedabove the top surface of the contact glass plate 14a, the shift controlpulley 57 is rotated in the direction indicated by the arrow B over arequired angle while the driving pulley 51 is not in motion. This causesthe second mirror 42 to be shifted in the direction indicated by thearrow M over a distance a half of the amount of movement of a point onthe periphery of the shift control pulley 57 so that the second mirror42 is brought closer to the first mirror 41 which stays still thus far.Accordingly, if it is structured such that shift control pulley 57 has aradius D and rotates by 1/800 of one complete rotation per step of thestepping motor, the amount of shift of the second mirror 42 is πD/800thereby allowing to shift the second mirror 42 to a desired positionaccurately by counting the number of pulses. Under the circumstances,when the optical system is operated in the manner described previously,a point of interest located above the contact glass plate 14a may beclearly shown on a sheet of copy paper.

FIG. 15 shows another embodiment of the present invention in which thepassing-through type lens 43 is provided to be shiftable to the rightalong the optical axis and the mirror 44' is also shiftable to the rightin an associated manner. If the distance l between a point of interestg' and the top surface of the contact glass plate 14a is relativelysmall, the shift amount s of the lens 43 and the shift amount m of themirror 44' in order to satisfy the in-focus condition at g' may beapproximated by s≅l and m≅l/2.

FIG. 16 shows a further embodiment of the present invention which isstructually similar to that shown in FIGS. 13 and 14. In thisembodiment, however, use is made of a reflecting type lens 43' insteadof the passing-through type lens 43 thereby allowing to make the wholedevice compact in size and to add the magnifying and/or reducingfunction in the size of a reproduced image. In this embodiment, sincethe second mirror 42' must be shifted in the direction perpendicular tothe reflecting surface of the lens 43', the focal point g' at a distancel separated from the top surface of the contact glass plate 14a is movedover a distance n in the forward direction of the scanning path.Assuming that the optical axis of the lens 43 is in parallel with thetop surface of the contact glass plate 14a and defining an angle θbetween the optical axis of the lens 43' and the optical path, such adiscrepancy n may be expressed as follows: ##EQU1## where the fact thatthe first mirror 41 meets at 45° with the top surface of the contactglass plate 14a has been taken into account. For example, if l=10 mm andθ=15°, then the discrepancy n=4.4 mm. The existence of such adiscrepancy indicates the existence of discrepancy in the image formingposition on the photosensitive drum 5. Therefore, in this embodiment,the timing of operation of the optical system must be made faster withrespect to the rotational velocity of the drum 5, or the timing ofsupplying a copy paper to the drum 5 must be delayed to compensate forthe discrepancy n.

FIG. 17 shows a further embodiment of the present invention in which aglass plate 60 is provided to be insertable in the optical path betweenthe lens 43 and the contact glass plate 14a to change the position ofthe focal point. As shown, the glass plate 60 is fixedly mounted on arotatable shaft 61 which may be rotated by a motor (not shown) or asolenoid (not shown) as required. Thus, by rotating the shaft 61 over apredetermined angle, the glass plate 60 may be moved between theoperative position in the optical path and the inoperative position outof the optical path.

It is to be noted that the distance l between the point of interest g'and the top surface of the contact glass plate 14a is the shortest whenthe glass plate 60 is held perpendicular to the optical axis. Under thecondition, denoting the refractive index of the glass plate 60 as N andits thickness as t, such a distance l may be expressed as follows:

    l=t-t/N.

Thus, for N=1.5, we have l=t/3. Therefore, if the angle α formed betweenthe optical axis and the glass plate 60 is gradually made smaller fromthe point of limit where l is the shortest, we have the followingrelation

    l=t/3 cosec α

which indicates that the point of interest g' may be continuously movedfurther away from the top surface of the contact glass plate 14a bymaking the angle α smaller.

FIG. 18 shows a still further embodiment of the present invention inwhich there is provided an auxiliary lens 62 which is a concave lenshaving a relatively low power. The auxiliary lens 62 is fixedly mountedon a rotatable shaft 63 which is driven to rotate by any conventionalmeans to bring the auxiliary lens 62 either into the operative positionin the optical path in front of the lens 43 or into the inoperativeposition outside of the optical path, e.g., 180° rotated from theoperative position. When located at the operative position, theauxiliary lens 62 cooperates with the lens 43 so that the focal point ofsuch a lens combination is slightly moved further away as compared withthe focal point of the lens 43 alone. In this embodiment, the majorpoint position of the lens 43 is slightly changed due to the insertionof the auxiliary lens 62. However, depending upon the position of thefocal point g' above the contact glass plate 14a or the design of thelens 43, such a change may be made as small as practically negligible.

It should further be noted that in the embodiment shown in FIG. 18, theauxiliary lens 62 may be moved along the optical path to change thedistance l between the focal point g' and the contact glass plate 14a.In other words, letting the focal distance of the lens 43 to be f₁, thefocal distance of the auxiliary lens 62 to be f₂, the gap between thelenses 43 and 62 to be L and the focal distance of the combined lenssystem to be f, we have the following equation among these parameters.##EQU2## In the above equation, the first and second terms are constantand the third term, in effect, is positive in value because the lens 43is a convex lens (f₁ >0) but the auxiliary lens 62 is a concave lens (f₂<0). Therefore, if the auxiliary lens 62 is moved in such a manner todecrease the distance L between the two lenses 43 and 62, then thecombined focal distance f can be made larger thereby allowing toincrease the distance l between the focal point g' and the contact glassplate 14a. On the contrary, if the auxiliary lens 62 is moved fartheraway from the lens 43, the distance l can be made smaller.

As described in detail above, in accordance with the present invention,the focal point may be varingly set at an arbitrary point located abovethe contact glass plate as well as at the top surface thereof just bymoving at least one element of the optical system, such as a lens, amirror, a glass plate and an auxiliary lens, which influences thecondition for image formation. The particular manner of such movementdepends upon the nature of each element, e.g., its function, shape andrelative positional relationship with the other elements. Accordingly,in accordance with the present invention, even such an original planewhich can only be located at a certain distance above the top surface ofthe contact glass plate may be properly and clearly reproduced on asheet of copy paper without causing deterioration of image quality orvariation in amount of illuminating light.

While the above provides a full and complete disclosure of the preferredembodiments of the present invention, various modifications, alternateconstructions and equivalents may be employed without departing from thetrue spirit and scope of the invention. Therefore, the above descriptionand illustration should not be construed as limiting the scope of theinvention, which is defined by the appended claims.

What is claimed is:
 1. An electrophotographic copying machine having anormal copy mode in which a two-dimensional copy is made from atwo-dimensional object and a three-dimensional copy mode in which atwo-dimensional copy is made from a three-dimensional object, saidcopying machine comprising:a photosensitive member; image forming meansincluding charging means for charging the surface of said photosensitivemember, exposure means for exposing the thus charged surface of saidphotosensitive member to said object to form its electrostatic latentimage, and developing means for developing said latent image to form avisual image; and switching means for switching between said normal copymode and three-dimensional copy mode, said switching means changing theconditions of at least one of said image forming means when switchedbetween the two modes.
 2. The copying machine of claim 1 wherein saidswitching means comprises an actuating lever which is depressed when acontainer for containing therein a three-dimensional object is placed inposition and slit-width controlling means for widening the width of anexposure slit when said actuating lever is depressed.
 3. The copyingmachine of claim 1 wherein said developing means includes a developingelectrode to which a predetermined voltage is applied and which isprovided to be movable with respect to the surface of saidphotosensitive member whereby said developing electrode is moved furtheraway from the surface of said photosensitive member when switched to thethree-dimensional copy mode from the normal copy mode.
 4. The copyingmachine of claim 1 wherein said switching means includes a first voltagecontrol means connected to means for illuminating said object and saidfirst voltage control means increases the level of voltage applied tosaid means for illuminating when switched to the three-dimensional copymode from the normal copy mode.
 5. The copying machine of claim 1wherein said switching means includes a second voltage control meansconnected to a developing electrode disposed in opposed relation withsaid photosensitive member and said second voltage control meansdecreases the level of voltage applied to said developing electrode whenswitched to the three-dimensional copy mode from the normal copy mode.6. The copying machine of claim 4 or 5 further comprising detectingmeans for detecting the presence of a container for containing therein athree-dimensional object and said detecting means is connected to saidfirst or second voltage control means whereby a change in the voltagelevel of said first or second voltage control means is automaticallycarried out.
 7. The copying machine of claim 6 wherein said detectingmeans includes a magnet mounted on said container and a magnet-operatedlead switch mounted on said copying machine.